Feedthrough Assembly and Method of Assembling a Feedthrough Assembly

ABSTRACT

A feedthrough assembly includes a main housing, a first inner housing positioned within the main housing and defining a plurality of first inner conduits, a second inner housing positioned within the main housing and defining a plurality of second inner conduits, and a chamber defined by an internal surface of the main housing, a first end of the first inner housing, and a first end of the second inner housing that faces the first end of the first inner housing. Each of the plurality of first inner conduits is aligned with a corresponding one of the plurality of second inner conduits. A cross-sectional area of the chamber varies along a longitudinal axis of the main housing.

TECHNICAL FIELD

The present disclosure relates generally to feedthrough assemblies, andmore particularly, to a feedthrough assembly through which optical orelectrical signals are transmitted in cables that extend through thefeedthrough assembly. Further, the present disclosure relates generallyto feedthrough assemblies in which may be housed, cables of varioustypes, such as optical fiber cables, electrical cables, or any othertype of cable through which an optical, electrical, thermal, or fluidsignal may be transmitted.

BACKGROUND

Component testing, such as optical component testing, often requirestransmitting an electrical or optical power signal to a component andmeasuring an output of the component. In order to determine how thecomponent will perform in particular environments, for example a spaceor high temperature environment, the component is tested in a chamberunder low or vacuum pressure. The test may evaluate whether thecomponent is susceptible to an operational irregularity that isthermally induced.

Generally, electrical or optical power signals are transmitted with acable from a non-vacuum environment through a feedthrough and to thecomponent in the vacuum environment. To ensure there is no loss ofvacuum pressure, the cable must be hermetically sealed through thefeedthrough. In an arrangement including multiple cables extendingthrough the feedthrough, heat may be generated in each cable as arespective signal is transmitted. A thermal path is needed for eachcable to remove heat. This prevents thermally induced operationalirregularities from occurring in a testing system device.

In addition, axial and lateral stress on cables due to bends orgenerally non-linear sections within the feedthrough lead to signal lossand/or cable failure. This is particularly evident in the case of cablestransmitting optical signals, and more specifically high-power opticalsignals. Accordingly, there is a need for each cable in an arrangementof multiple cables to extend, and be maintained to extend, along astraight path through the feedthrough.

SUMMARY

According to an aspect of the present disclosure, a feedthrough assemblyis described which includes a main housing, a first inner housingpositioned within the main housing and defining a plurality of firstinner conduits, a second inner housing positioned within the mainhousing and defining a plurality of second inner conduits, and a chamberdefined by an internal surface of the main housing, a first end of thefirst inner housing, and a first end of the second inner housing thatfaces the first end of the first inner housing. Each of the plurality offirst inner conduits is aligned with a corresponding one of theplurality of second inner conduits. A cross-sectional area of thechamber varies along a longitudinal axis of the main housing.

According to another aspect of the present disclosure, a signalconveying system includes a base, a cover defining a chamber with thebase, a feedthrough assembly mounted to the base, and a plurality ofcables extending through the feedthrough assembly into the chamber andconfigured to transmit signals. The feedthrough assembly includes a mainhousing, at least one housing positioned within the main housing andincluding an internal wall that defines a plurality of conduits, avolume defined by an internal surface of the main housing, and at leastone sealing material provided at least throughout the volume. Each cableextends through the main housing and a respective conduit along arespective continuous axis. In addition, the sealing material and theinternal wall isolate each cable from a respective remainder of theplurality of cables.

Another aspect of the present disclosure provides a method of assemblinga feedthrough assembly including providing a first and a second housingeach including plural conduits there through, aligning each conduit ofthe first housing with a respective conduit of the second housing toform aligned conduit pairs, passing at least two optical fiber cablesthrough separate conduit pairs, and supplying a sealing material intothe separate conduit pairs through a central conduit of at least one ofthe first housing and the second housing.

Yet another aspect of the present disclosure provides a method oftesting a component in a testing system including a feedthrough assemblyhaving a housing defining a plurality of conduits and an optical fibercable extending through each conduit. The method includes providing atleast one optical signal to the feedthrough assembly, transmitting theoptical signal through a straight path from a first end to a second endof the feedthrough assembly, and transmitting the optical signal fromthe second end to the component and measuring an output of thecomponent. The straight path is defined by at least one optical fibercable in direct contact with a sealing material that fills thefeedthrough assembly and maintains each optical fiber cable to extendalong a respective straight path within the feedthrough assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a perspective view of a test testing system,according to an aspect of the present disclosure.

FIG. 2 illustrates a perspective view of a testing chamber, according toan aspect of the present disclosure.

FIG. 3 illustrates a top view of an enlarged portion of FIG. 2,identified as Detail 3.

FIG. 4 illustrates a front elevation view of the first feedthroughassembly and the second feedthrough assembly of FIG. 3.

FIG. 5 illustrates a partial view of a feedthrough assembly, accordingto an aspect of the present disclosure.

FIG. 6 illustrates an enlarged portion of FIG. 5, identified as Detail6.

FIG. 7A illustrates a front perspective view of an inner housing,according to an aspect of the present disclosure.

FIG. 7B illustrates a rear perspective view of the inner housing of FIG.7A.

FIG. 8A illustrates a schematic elevation view of an inner housingarrangement, according to an aspect of the present disclosure.

FIG. 8B illustrates a schematic elevation view of the inner housingarrangement of FIG. 8A, taken from line 8B-8B.

FIG. 9 illustrates a schematic partial view of a housing assembly,according to an aspect of the present disclosure.

FIG. 10 illustrates a schematic isometric view of a cable and housingassembly, according to an aspect of the present disclosure.

FIG. 11 illustrates a schematic cross-sectional view of the feedthroughassembly of FIG. 5.

FIG. 12 illustrates flow paths through the feedthrough assembly asillustrated in FIG. 11.

FIG. 13 illustrates a fixture constructing a feedthrough assembly,according to an aspect of the present disclosure.

DETAILED DESCRIPTION

Aspects of the disclosure will now be described in detail with referenceto the drawings, wherein like reference numbers refer to like elementsthroughout, unless specified otherwise.

It is noted that as used in the specification and the appending claimsthe singular forms “a,” “an,” and “the” can include plural referencesunless the context clearly dictates otherwise.

Unless specified otherwise, the terms “substantial” or “substantially”as used herein mean “considerable in extent,” or “largely but notnecessarily wholly that which is specified.”

Recitation of ranges of values herein are merely intended to serve as ashorthand method of referring individually to each separate valuefalling within the range, unless otherwise indicated herein, and eachseparate value is incorporated into the specification as if it wereindividually recited herein. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context.

FIG. 1 illustrates a perspective view of a test testing system 100,according to an aspect of the present disclosure. The testing system 100includes a controller 102 that operates at least one pump 104. The pump104 is operatively connected to a cover 106.

FIG. 2 illustrates a perspective view of a testing chamber 200,according to an aspect of the present disclosure. The testing chamber200 is defined by an interior of the cover 106 and a base 202. The pump104 may apply a vacuum pressure through the cover 106 to the testingchamber 200 to form a vacuum. Alternatively, the pump may pressurize thetesting chamber 200 in order for the testing chamber 200 to be at adifferent pressure than a pressure outside of the cover 106. A platform204 is positioned within the testing chamber 200 by first mounting rods206. The first mounting rods 206 extend vertically within the testingchamber 200 and include rod holders 208 that receive second mountingrods 210 extending in a horizontal direction from the platform 204. Acomponent 212 may be positioned on top of the platform 204 and receivesignals through input cables 214 a and either output or transmit signalsthrough output cables 214 b. The input cables 214 a and the outputcables 214 b may extend from an area outside of the testing chamber 200(e.g. an area under atmospheric pressure) into the testing chamber 200through a flange assembly 216 extending from an outer surface 218 a of awall 218 of the base 202. An inner surface 218 b of the wall 218 definesa bottom portion of the testing chamber 200.

FIG. 3 illustrates a top view of an enlarged portion of FIG. 2,identified as Detail 3. As illustrated in FIG. 3, a first feedthroughassembly 300 a and a second feedthrough assembly 300 b may be secured tothe flange assembly 216 by respective fastening collars 302. Inparticular, each of the fastening collars 302 may be coupled with anO-ring to couple a respective one of the first feedthrough assembly 300a and the second feedthrough assembly 300 b to a mating flange 304 ofthe flange assembly 216, and thereby create a seal between the testingchamber 200 and each of the feedthrough assemblies (300 a, 300 b). Eachof the fastening collars 302 may be a threaded fastener, such as aneural nut or other fastening device. The fastening collars 302 allowthe feedthrough assemblies (300 a, 300 b) to be detached from the flangeassembly 216 without a requirement that the mating flange 304 or amounting flange 306 of the flange assembly 216 be replaced. The mountingflange 306 is attached to the mating flange 304 by a plurality of nutsand bolts or other fastening mechanisms known in the art (e.g.adhesives, clamps, screws, etc.). The mounting flange 306 is positionedat the end of a duct 308 which extends from a location on the outersurface 218 a of the wall 218 corresponding to a location of a bore 310that opens on the inner surface 218 b to the test chamber 200. The inputcables 214 a may be housed in a respective cable bundle conduit 312, andextend through the first feedthrough assembly 300 a, the mating flange304, the mounting flange 306, and the bore 310, and into the testingchamber 200. Similarly, the output cables 214 b may be housed in arespective cable bundle conduit 312, and extend through the secondfeedthrough assembly 300 b, the mating flange 304, the mounting flange306, and the bore 310, and into the testing chamber 200.

FIG. 4 illustrates a front elevation view of the first feedthroughassembly 300 a and the second feedthrough assembly 300 b. A main housing406 of each of the first feedthrough assembly 300 a and the secondfeedthrough assembly 300 b may extend from a first end 408 to a secondend 410. A portion of each input cable 214 a and each output cable 214 bextending from the first end 408 of a respective main housing 406includes a first sleeve 418. A portion of each input cable 214 a andeach output cable 214 b extending from a second end 410 of a respectivemain housing 406 includes a second sleeve 420. The first sleeve 418 andthe second sleeve 420 may each be formed from a polymer material havingoptical, heat, or electrical insulating characteristics. The firstsleeve 418 and the second sleeve 420 may be formed from the same ordifferent materials. For example, the first sleeve 418 may be formedfrom a material suitable for exposure to a vacuum pressure, and thesecond sleeve 420 may be formed from a material suitable for exposure toatmospheric pressure.

The first end 408 of each of the first feedthrough assembly 300 a andthe second feedthrough assembly 300 b is configured to be attached tothe mating flange 304 with respective fastening collars 302 illustratedin FIG. 3. As explained in more detail below, the first end 408 of eachof the feedthrough assemblies (300 a, 300 b) will be sealed by amaterial that is suitable for maintaining a sealed connection whilebeing subjected to vacuum pressure during an operation of the testingsystem 100 illustrated in FIG. 1. Further, as explained in more detailbelow, the material used to seal the first ends 408 may be differentthan a material used to seal respective second ends 410 of thefeedthrough assemblies (300 a, 300 b). In order to aid an operator ortechnician that is coupling one of the feedthrough assemblies (300 a,300 b) to the flange assembly 216, the first sleeve 418 may be adifferent color than the second sleeve 420. Thus, the operator ortechnician may be able to easily recognize the color of the sleeve thatcorresponds to the end of one the feedthrough assemblies (300 a, 300 b)that is to be coupled to the mating flange 304 of the flange assembly216.

FIG. 5 illustrates a partial view of a feedthrough assembly 300,according to an aspect of the present disclosure. The feedthroughassembly 300 is an exemplary embodiment of the first feedthroughassembly 300 a and the second feedthrough assembly 300 b, and includes arespective main housing 406 through which respective cables 214 extend.Within the main housing 406, a first inner housing 500 a and a firstouter housing 502 a may be positioned on one side of a center 501 of themain housing 406 closer to the first end 408. As illustrated in FIG. 5,a second inner housing 500 b and a second outer housing 502 b may alsobe positioned within the main housing 406 on the other side of thecenter 501, closer to the second end 410. It will be appreciated thatthe housings (500 a, 500 b, 502 a, 502 b) may be positioned in otherarrangements relative to the center 501 of the main housing 406. Eachcable 214 extends through each of the housings (500 a, 500 b, 502 a, 502b).

A cable core 504 of each cable 214 extends through a feedthrough chamber506 that is defined by the first inner housing 500 a, the second innerhousing 500 b, and an inner surface 505 of the main housing 406. Thecable core 504 may be a core of an optical fiber which may be made ofglass, or more generally, made of optically transparent fusion productsof inorganic materials that have been cooled to a rigid state withoutcrystalizing. Alternatively, the cable core 504 may be formed from anelectrically conductive material, such as copper. In the case of anoptical fiber, each cable core 504 will have an index of refraction forlight transmission, and each cable 214 may include a layer of claddingseparating a respective cable core 504 from a respective first sleeve418 and a respective second sleeve 420. The cladding may have an indexof refraction that is lower than the index of refraction of the cablecore 504.

A first sealing material 508 may be provided at the second end 410 ofthe main housing 406 surrounding portions of the cables 214 includingsecond sleeves 214. The first sealing material 508 may be fast settingepoxy or resin suitable for exposure to atmospheric pressures. A secondsealing material 510 may be provided to fill the feedthrough chamber506. The second sealing material 510 may be a thermally conductiveadhesive material such as a low vapor pressure epoxy or resin. Inaddition, the second sealing material 510 may surround, and as describedin more detail below, fill the first inner housing 500 a, the firstouter housing 502 a, the second inner housing 500 b, and the secondouter housing 502 b. In addition, the second sealing material 510 maysurround each of the cables 214 at the first end 408 of the main housing406.

FIG. 6 illustrates an enlarged portion of FIG. 5, identified as Detail6. As illustrated in FIG. 6, a cross-sectional area of the feedthroughchamber 506 varies along a longitudinal axis 600 of the main housing 406according to a shape of a first end 602 of the first inner housing 500 aand a shape of a first end 602 of the second inner housing 500 b. Thefirst end 602 of the first inner housing 500 a may be tapered and facethe first end 602 of the second inner housing 500 b, and a second end604 of the first housing 500 a may have a planar shape and extend alonga plane perpendicular to the longitudinal axis 600. Similarly, the firstend 602 of the second inner housing 500 a may be tapered and face thefirst end 602 of the first inner housing 500 b, and a second end 604 ofthe second inner housing 500 a may have a planar shape and extend alonga plane perpendicular to the longitudinal axis 600. Thus, thecross-sectional area of the feedthrough chamber 506 may increase in adirection from the first inner housing 500 a towards the center 501 ofthe main housing 406, and continuing in the same direction, decreasefrom the center 501 towards the second inner housing 500 b.

A portion of the cable core 504 of each cable 214 extends through atleast a portion of the first inner housing 500 a, the feedthroughchamber 506, and at least a portion of the second inner 500 b without arespective cladding, first sleeve 418, and second sleeve 420 over anexposed core cable length 608. An exposed core cable length 608 may bethe same for each cable 214, and may extend from the second end 604 ofthe first inner housing 500 a to the second end 604 of the second innerhousing 500 b. For each cable 214, a respective cable core 504 isimmediately surrounded by the second sealing material 510 across anentire length of the feedthrough chamber 506.

FIG. 7A illustrates a front perspective view of an inner housing 500,according to an aspect of the present disclosure. The inner housing 500is an exemplary embodiment of the first inner housing 500 a and thesecond inner housing 500 b, and includes a respective first end 602 anda respective second end 604. FIG. 7B illustrates a rear perspective viewof the inner housing 500 of FIG. 7A. As illustrated in FIGS. 7A and 7B,an inner central conduit 700 is defined within the inner housing 500 toextend from a slot 702 in the first end 602, to a planar through hole703 in the second end 604. A plurality of inner cable conduits 704 aredefined by an internal wall 705 of the inner housing 500, and extendfrom angled through-holes 706 formed in the first end 602 as illustratedin FIG. 7A, to planar through holes 708 formed in the second end 604 ofthe inner housing 500 as illustrated in FIG. 7B. A width (e.g. diameter)of each inner cable conduit 704 may be sized to accommodate the cablecore 504 of a respective cable 214, or a combination of the cable core504, cladding, and either of the first sleeve 418 or the second sleeve420 of the respective cable 214.

The inner cable conduits 704 are evenly spaced in an annular directionabout a longitudinal axis 710 of the inner housing 500. Thus, the innercable conduits 704 are arranged in a row 712 of conduits extending fromthe first end 602. In particular, each inner cable conduit extends froma same axial position along, and is positioned a same radial distancefrom the longitudinal axis 710 of the inner housing 500. It will beappreciated that the inner housing 500 may include multiple rows of theinner cable conduits 704, with each row spaced a respective radialdistance from the longitudinal axis 710. In an arrangement with multiplerows 712, spacing in the annular direction between inner cable conduits704 could be the same for each row 712. Accordingly, rows 712 closer tothe longitudinal axis 710 in a radial direction will have fewer innercable conduits 704 than rows 712 further from the longitudinal axis 710.Alternatively, within each row 712, inner cable conduits 704 may bespaced in the annular direction so that each row 712 has the same numberof inner cable conduits 704. It will be appreciated that the inner cableconduits 704 may be provided in multiple arrangements, includingarrangements of inner cable conduits 704 that are not equally spaced inthe annular direction and/or arranged in rows.

As illustrated in FIG. 7A, the slot 702 extends across an entire widthof the inner housing 500 between flanks 714 which are tapered along thelongitudinal axis 710 and define as least a portion of a tapered shapeof the first end 602. It will be appreciated that the flanks 714 may beformed as rounded or flat tapered surfaces, and an angle of a taper foreach flank 714 may be constant, increasing, or decreasing in a directionfrom the first end 602 towards the second end 604. A length of the slot702 along the longitudinal axis 710 of the inner housing 500 maycorrespond to a length of a tapered portion of the first end 602. Itwill be appreciated that the length of the slot 702 in otherconfigurations may increase or decrease along the width of the innerhousing 500 from an edge of the inner central conduit 700 (e.g. asurface defining an end of the slot 702 opposite to an open end may beangled along the width of the inner housing 500). As illustrated in FIG.7A, a leading edge 716 of the inner housing 500 is open such that aportion of the slot 702 corresponding to the inner central conduit 700is not blocked from an area in front of the first end 602 of the innerhousing 500. Alternatively, the inner housing 500 may include a thinlayer (not shown) extending between the flanks 714 for a portion of thelength of the slot 702 corresponding to the leading edge 716. A width ofthe thin layer may be equal to a width (e.g. diameter) of the innercentral conduit 700.

During a filling process, described in more detail below, the secondsealing material 510 is supplied to the feedthrough assembly 300. Theslot 702 of the first inner housing 500 a provides an outlet throughwhich the second material 510 may be supplied to the feedthrough chamber506. The second sealing material 510 may be conveyed through the slot702 of the first inner housing 500 a and diverted by the flanks 714 ofthe second housing 500 b so as to be dispersed throughout thefeedthrough chamber 506. The second sealing material 510 may also flowinto the slot 702 of the second housing 500 b.

FIG. 8A illustrates a schematic elevation view of an inner housingarrangement 800, according to an aspect of the present disclosure. Theinner housing arrangement 800 includes the first inner housing 500 a andthe second inner housing 500 b illustrated in FIGS. 5 and 6. A slot 702is defined between flanks 714 of the first inner housing 500.

FIG. 8B illustrates a schematic elevation view of the inner housingarrangement 800 of FIG. 8A, taken from line 8B-8B. A slot 702 is definedbetween flanks 714 of the second inner housing 500 b. The second innerhousing 500 b is positioned relative to the first housing 500 a so thatthe flanks 714 of the second inner housing 500 b extend along a planethat is perpendicular to a plane of the flanks 714 of the first housing500 a. More specifically, the second housing 500 b is rotated so theflanks 714 of the second inner housing 500 b are offset by 90° relativeto the flanks 714 of the first housing 500 a. It will be appreciatedthat an angle of offset may be an angle other than 90°, such that theflanks 714 of the second inner housing 500 b divert and distribute thesecond sealing material 510 being supplied sufficiently to fill anyspace within the feedthrough assembly 300 that is not occupied by thecables 214 or the housings (500 a, 500 b, 502 a, 502 b).

In the inner housing arrangement 800, each inner cable conduit 704 ofthe first inner housing 500 a is paired with a corresponding inner cableconduit 704 of the second housing 500 b. Each pair of inner cableconduits 704 are aligned such that one of the cables 214 can extendthrough a respective pair of inner cable conduits 704 along a straightpath. As described in more detail below with reference to FIGS. 11 and12, each of the first outer housing 502 a and the second outer housing502 b may include outer cable conduits 1104 which are aligned,respectively, with the inner cable conduits 704 of the first innerhousing 500 a and the second inner housing 500 b. Thus, each cable 214extends through the feedthrough assembly 300 along a respective straightpath.

FIG. 9 illustrates a schematic partial view of a housing assembly 900,according to an aspect of the present disclosure. The housing assembly900 includes the main housing 406, the inner housing arrangement 800,and the first outer housing 502 a and the second outer housing 502 b onopposite sides of the inner housing arrangement 800. The feedthroughchamber 506 is entirely defined within the housing assembly 900.

The housings (500 a, 500 b, 502 a, 502 b) may be secured in the mainhousing 406 by an adhesive material. For example, the housings (500 a,500 b, 502 a, 502 b) may be coated with an adhesive material andinserted into the main housing 406; and the main housing 406 may remainin a stationary position while the adhesive material is allowed to set.The adhesive material may be the same material as the second sealingmaterial 510, or any other type of thermally conductive adhesivematerial. According to another aspect of the present disclosure, each ofthe housings (500 a, 500 b, 502 a, 502 b) may be formed from a materialthat is capable of being deformed to a relative degree, and shaped toinclude an outermost diameter substantially the same as a diameter ofthe inner surface 505 of the main housing 406. Upon insertion into themain housing 406, the housings (500 a, 500 b, 502 a, 502 b) may becompressed to a degree for which a shape and alignment of the cableconduits (704, 1104) are substantially maintained, and secured via aninterference fit with the inner surface 505 in the main housing 406.

Prior to inserting the housings (500 a, 500 b, 502 a, 502 b) in the mainhousing 406, the first inner housing 500 a may be rotated relative tothe second housing 500 b so that the flanks 714 of the first housing 500a are perpendicular to the flank 714 of the second inner housing 500 b,or offset by a desired angle, to provide the inner housing arrangement800. In addition, at least one rigid wire or cable may be passed througha pair of inner cable conduits 704 and corresponding outer cableconduits 1104 (FIGS. 11 and 12), to align the cable conduits (704, 1104)before the housings (500 a, 500 b, 502 a, 502 b) are inserted into themain housing 406. In the case of an interference fit, a rigid wire orcable may be passed through more than one pair of inner cable conduits704 and corresponding outer cable conduits 1104.

Alternatively, each of the housings (500 a, 500 b, 502 a, 502 b) can beformed with and additional conduit that is only used to receive a wirefor alignment purposes. The additional conduit would not accommodate acable 214, but would be later filled with the second sealing material510 after the wire is removed. According to another aspect of thepresent disclosure, the first inner housing 500 a may include a notch orrecess formed in a respective flank(s), which corresponds to a registeror other type of protrusion formed in a respective flank(s) of thesecond inner housing 500 b. Accordingly, when the first inner housing500 a is properly aligned with the second inner housing 500 b, theregister or protrusion will be received in the notch or recess. It willbe appreciated that each of the inner housings (500 a, 500 b) may have anotch and a protrusion formed on respective flanks. According to yetanother aspect of the present disclosure, the inner housing arrangement800 could be formed as a single housing with slots 702 arranged in themanner illustrated in FIGS. 5, 6, 8A, and 8B. Thus, a need to align thefirst inner housing 500 a relative to the second inner housing 500 bbefore inserting the inner housing arrangement 800 into the main housing406 can be obviated, and the inner housings (500 a, 500 b) will remainaligned during an assembly process.

Once the housing assembly 900 is constructed the cables 214 may beinserted into the housing assembly 900. Each cable 214 includes theexposed core cable length 608, a first sleeve cable length 902 includingthe first sleeve 418 surrounding the cladding and the core 504, and asecond sleeve cable length 904 including the second sleeve 420surrounding the cladding and the core 504. The cables 214 may beinserted into the housing assembly 900 with the sleeves (418, 420), orthe sleeves (418, 420) can be slid over the cables 214 after the cables214 are inserted. For each cable 214, the first sleeve cable length 902may be positioned at least within the first outer housing 502 a, and thesecond sleeve cable length 904 may be positioned at least within thesecond outer housing 502 b. According to one aspect of the presentdisclosure a portion of each first sleeve cable length 902 may bepositioned in a respective inner cable conduit 704 of the first innerhousing 500 a, and a portion of each second sleeve cable length 902 maybe positioned in a respective inner cable conduit 704 of the secondinner housing 500 b. According to another aspect of the presentdisclosure, a portion of each exposed core cable length 608 may bepositioned in the first outer housing 502 a and the second outer housing502 b.

FIG. 10 illustrates a schematic isometric view of a cable and housingassembly 1000, according to an aspect of the present disclosure. Thecable and housing assembly 1000 includes the cables 214, the first innerhousing 500 a, the first outer housing 502 a, the second inner housing500 b, and the second outer housing 502 b. The cable and housingassembly 1000 defines an internal frame 1002 of the feedthrough chamber506 with the first ends 602 of the first inner housing 500 a and thesecond inner housing 500 b. The cables 214 may be positioned in thehousings (500 a, 500 b, 502 a, 502 b) after the pairs of inner cableconduits 704 and corresponding outer cable conduits 1104 (FIGS. 11 and12) are aligned to provide the inner housing arrangement 800, and beforethe cable and housing assembly 1000 is inserted within the main housing406. For each cable 214, a portion of the first sleeve cable length 902may be positioned at least within the first outer housing 502 a, and aportion of the second sleeve cable length 904 may be positioned at leastwithin the second outer housing 502 b. In order to minimize the numberof components that may rotate during insertion, a thermally conductiveadhesive may be applied between the first inner housing 500 a and thefirst outer 500 b, and between the second inner housing 500 b and thesecond outer housing 502, prior to the cable and housing assembly 1000being inserted into the main housing 406.

FIG. 11 illustrates a schematic cross-sectional view of the feedthroughassembly 300 of FIG. 5. In particular, the feedthrough assembly 300 isshown prior to being filled with the second sealing material 510. Asillustrated in FIG. 11, an outer central conduit 1100 is defined by thefirst outer housing 502 a and is in fluid communication with the innercentral conduit 700 of the first inner housing 500 a, and an outercentral conduit 1100 of the second outer housing 502 b is in fluidcommunication with the inner central conduit 700 of the second innerhousing 500 b. The first outer housing 502 a includes outer cableconduits 1104 that are in alignment with the inner cable conduits 704 ofthe first inner housing 500 a, the inner cable conduits 704 of thesecond inner housing 500 b, and outer cable conduits 1104 of the secondouter housing 502 b. At least a portion of each cable 214 within arespective outer cable conduit 1104 of the first outer housing 502 aincludes the first sleeve 418, and at least a portion of each cable 214within a respective outer cable conduit 1104 of the second outer housing502 b includes the second sleeve 420. As illustrated in FIG. 11, thecentral conduits (700, 1100) are coaxial with the longitudinal axis 600of the feedthrough assembly 300.

According to one aspect of the present disclosure, the diameter of theouter cable conduits 1104 may be sized according to a diameter of theportions of the cables 214 with the first sleeves 418 or the secondsleeves 420, and the diameter of the inner cable conduits 704 may besized according to a diameter of the cable core 504. In particular, asillustrated in FIGS. 11 and 12, the outer cable conduits 1104 may have alarger diameter than a diameter of the inner cable conduits 704. Forexample, a diameter of the outer cable conduits 1104 can be two timesthe size of a diameter of the inner cable conduit 704. During assembly,the first sleeve 418 and the second sleeve 420 can be removed from eachof the cables 214 before the cables are inserted into the housings (500a, 500 b, 502 a, 502 b). Once inserted, the first sleeve 418 and thesecond sleeve 420 of each cable 214 can be slid over a respective end ofthe cable core 504 of a respective cable 214. A radial portion of eachouter cable conduit 1104 will overlap with a portion of the internalwall 705 surrounding the smaller diameter inner cable conduits 704 atthe second ends 604 of the first inner housing 500 a and the secondinner housing 500 b. As such, when the first sleeves 418 and secondsleeves 420 are slid over the cable cores 504 and into the outer cableconduits 1104 of the first outer housing 502 a and the second outerhousing 502 b, the progress of each sleeve will be stopped by theinternal walls 705 of the first inner housing 500 a and second innerhousing 500 b. Alternatively, the outer cable conduits 1104 may bedefined to have a diameter the same as a diameter of the inner cableconduits 704.

According to another aspect of the present disclosure, the diameter ofthe outer cable conduits 1104 may be sized relative to the diameter ofthe inner cable conduits 704 to promote a flow of the second sealingmaterial 510 during the filling process of the feedthrough assembly 300,and a completeness of filling the spaces around the cables 214 withinthe cable conduits (704, 1104). According to one aspect of presentdisclosure, where multiple rows 714 of the inner cable conduits 704 andcorresponding rows of outer cable conduits 1104 are provided, diametersof cable conduits (704, 1104) in one row may be different from diametersof the cable conduits (704, 1104) in another row in order to accommodatedifferent sized cables 214.

During the filling process, an outlet 1106 of a fluid delivery device1108 is inserted into an end of the first outer housing 502 a facing thefirst end 408 of the main housing 406. The outlet 1106 may be a needleor other type of conduit having a diameter substantially the same as, orless than, the diameter of the outer central conduit 1100 of the firstouter housing 502 b. The fluid delivery device 1108 may include asyringe or nozzle operatively attached to the outlet 1106.

FIG. 12 illustrates flow paths (1200, 1202, 1204, 1206, 1208) throughthe feedthrough assembly 300 as illustrated in FIG. 11. During aninitial step of the filling process for the feedthrough assembly 300,the first sealing material 508 (not shown) is supplied to the second end410 of the main housing 406 and allowed to set in order to provide aplug which stops the second sealing material 510 from flowing out of thesecond end 410 of the main housing 406. During the time when the firstsealing material 508 is supplied, the feedthrough assembly 300 may beorientated 180° from an orientation shown in FIG. 11 so that the secondend 410 of the main housing 406 faces in an upward direction.

After the first sealing material 508 sets, the feedthrough assembly 300may be rotated 180°. Next, the fluid delivery device 1108 may beattached or inserted into the outer central conduit 1100 of the firstouter housing 502 a, and the second sealing material 510 may be suppliedthrough the outlet 1106. The sealing material 510 may flow along a firstflow path 1200 defined by the outer and inner central conduits (700,1100) of the first outer and inner housings (502 a, 500 a). Next, thesealing material 510 may flow through a second flow path 1202 defined bythe slot 702, in a direction perpendicular to a direction of flowthrough the first flow path 1200. The second sealing material 510 mayflow along the second flow path 1202 into the feedthrough chamber 506.The second sealing material 510 may flow along a third flow path 1204defined by the inner and outer central conduits (700, 1100) of thesecond inner and outer housings (500 b, 502 b) until being stopped bythe first sealing material 508. The second sealing material 510 willaccumulate and fill the third flow path 1204, while at the same time,being diverted by the flanks 714 of the second inner housing 500 b intofourth flow paths 1206 defined by the inner and outer cable conduits(704, 1104) of the second inner and outer housings (500 b, 502 b).

According to one aspect of the present disclosure, some of the secondmaterial 510 may flow through the third flow path 1204 and fill a space(not shown) between the first sealing material 508 and an end of thesecond outer housing 502 that faces the second end 410 of the mainhousing 406, more rapidly than the second sealing material 510 flowingin the fourth flow paths 1206. Accordingly, the fourth flow paths 1206may begin to be filled in a direction from the space between the firstsealing material 508 and the second outer housing 502 b towards thefeedthrough chamber 506. Alternatively, in a case where the first innerhousing 500 a is provided with a thin layer (not shown) extendingbetween the flanks 714 of the first inner housing 500 a as previouslydiscussed, more of the flow of the second material 510 may be divertedby the flanks 714 of the second inner housing 500 b into the angledthrough holes 706 of the second inner housing 500 b and into the fourthflow paths 1206. Accordingly, the fourth flow paths 1206 may fill morerapidly than the third flow path 1204, and the third flow path 1204 maybegin to be filled in the direction from the space between the firstsealing material 508 and the second outer housing 502 b towards thefeedthrough chamber 506.

During, or after, the time the second sealing material 510 fills thethird and fourth flow paths (1204, 1206), the feedthrough chamber 506and fifth flow paths 1208 defined by the inner and outer cable conduits(704, 1104) of the first inner and outer housings (500 a, 502 a), may befilled with the second sealing material 510. In the feedthrough chamber506, the cable cores 504 of the cables are completely surrounded by, andthus in direct contact with, the second sealing material 510.

Once the filling process is complete, between the first end 408 of themain housing 406 and the first sealing material 510, each cable 214 iscompletely surrounded by the second sealing material 510. Accordingly,any space between walls defining the inner and outer cable conduits(704, 1104) and the cables 214, whether it be the cable cores 504 orportions of each cable 214 including the first sleeve 418 or the secondsleeve 420, is completely filled with the second sealing material 510.In addition, any space between the inner surface 501 of the main housing406 and outer surfaces of the housings (500 a, 500 b, 502 a, 502 b) isalso filled with the second sealing material 510. Thus, each cable 214may be hermetically sealed, and there may be substantially no pockets ofair, within the main housing 406 of the feedthrough assembly 300. Asdescribed in more detail below, the distribution of second sealingmaterial 510 eliminating pockets of air and hermetically sealing eachcable 214, coupled with the isolation of each cable 214 by encapsulatingeach cable 214 with the thermally conductive second sealing material510, may be advantageous for an application of the feedthrough assembly300 incorporating optical fiber cables. However, it will be understoodthat the cables 214 may be any type of cable that can transmit anelectrical, optical, thermal, or fluid signal.

FIG. 13 illustrates a fixture 1300 for constructing a feedthroughassembly, according to an aspect of the present disclosure. A base 1302of the fixture 1300 is attached to a mounting structure 1304 formed witha recess 1306. At least one standoff 1308 extends from the recess 1306.The standoff 1308 may include a large diameter portion 1310 and a smalldiameter portion 1312 extending from the large diameter portion 1310. Adiameter of the small diameter portion 1312 is less than an innerdiameter of the main housing 406. Each standoff 1308 may be formed as asingle component that is part of the mounting structure 1304 of thefixture 1300, or as a separate component that can be detachably fixed toa surface of the recess 1306 in the mounting structure 1304. In the caseof the latter, each standoff 1308 can be replaced with another standoffhaving large and small diameter portions different than the standoff1308 that is being replaced, in order to accommodate housings ofdifferent sizes.

FIG. 13 illustrates a portion of a construction of, for example, thefirst feedthrough assembly 300 a before the first sealing material 508is applied to the second end 410. It will be appreciated that thefollowing procedure for constructing the first feedthrough assembly 300a may be applied to construct the second feedthrough assembly 300 b. Thefirst feedthrough assembly 300 a is positioned on top of a respectivestandoff 1308 and the cables 214 a extend out of the base 1302. Thesmall diameter portion 1312 of the standoff 1308 is positioned inside ofthe first end 408. Accordingly, during construction, the small diameterportion 1312 supports and maintains the housings (500 a, 500 b, 502 a,502 b) together in a desired location within the main housing 406. Thus,the fixture 1300 holds the first feedthrough assembly 300 a in placeduring a time when the first sealing material 508 is applied to thesecond end 410 and allowed to set. Following the setting of the firstsealing material 508, the first feedthrough assembly 300 a is taken offof the standoff 1308 and rotated 180° so that the outlet 1106 of thefluid delivery device 1108 can be inserted into the central conduit 1100as illustrated in FIG. 11, and the second sealing material 510 can besupplied. According to an aspect of the present disclosure, the standoff1308 may be received in and removed from a second recess within themounting structure 1304. During construction, the first feed throughassembly 300 a may be positioned in the second recess and held in placethereby as the second sealing material 510 flows through the flow paths(1200, 1202, 1204, 1208).

Low pressure testing may be used to evaluate optical componentperformance in space based systems, or to exacerbate the conditions anoptical component will be exposed to in a high-temperature environment.In particular, in a low pressure testing environment, such as a vacuumenvironment, convection may be eliminated as a method for heat removaland therefore increase a probability and effect of operationalirregularities that are thermally induced. In addition, where opticalfibers are implemented in testing applications, bends or generallynon-linear sections of the optical fiber cables, especially sectionswhere cores of the optical fiber cables are not surrounded by claddingor sleeves, may be subject to axial stress that can lead to failure andpositional orientations increasing optical signal loss through theoptical fiber cable.

According to one aspect of the present disclosure, the component 212illustrated in FIG. 2, may be an optical component that may beincorporated in, for example, a space based system. The pump 104 of thetesting system 100 illustrated in FIG. 1, may apply a vacuum pressure tothe testing chamber 200 in order to test the optical performance of thecomponent 212 under conditions the component 212 may be subject to. Theinput cables 214 a and the output cables 214 b of FIG. 2 may be opticalfiber cables. For each feedthrough assembly (300 a, 300 b), the cableconduits (704, 1104) coupled with the second sealing material 510,hermetically seal each optical fiber cable within the main housing 406.The hermetic seal provided around each optical fiber cable, and a sealof the main housing 406 provided by the combination of the first sealingmaterial 508 and the second sealing material 510, maintains the testingchamber 104 under a vacuum or low pressure, as opposed to, for example,an atmospheric pressure outside of the cover 106.

During operation, substantial amounts of heat can be generated in eachoptical fiber cable core as a respective optical signal is conveyedthrough the optical fiber cable core. For each feedthrough assembly (300a, 300 b), the physical separation between adjacent optical fiber cablesprovided by the cable conduits (704, 1104) and the second sealingmaterial 510, may prevent excessive heating within the main housing 406.Due to the thermal conductivity of the second sealing material 510, heatgenerated in each of the optical fiber cables may be conducted from theoptical fiber cables through thermal paths provided by the secondsealing material 510, walls of the housings (500 a, 500 b, 502 a, 502b), and a wall of the main housing 406. In other words, heat generatedwithin each optical fiber cable may dissipate through thermal pathsprovided within the feedthrough assemblies (300 a, 300 b). Further, theabsence of pockets of air within the feedthrough assemblies prevents thecreation of hot spots that can rapidly expand and cause thermallyinduced operational irregularities in the testing system 100.

In addition, the feedthrough assembly 300 allows for multiple opticalfiber cables to pass through a single feedthrough while maintainingextremely low lateral and axial stress on each optical fiber cable. As aresult, each optical fiber cable extends along a substantially uniformstraight path which may eliminate an occurrence of optical signal lossfrom the optical fiber cables within the feedthrough assembly 300.Another advantage provided by dedicated cable conduits for each opticalfiber cable, or electrical cable in other applications, is increasedefficiency in assembling a feedthrough.

Manufacturing methods such as additive manufacturing (AM) or SolidFreeform Fabrication (SFF) of metal parts can be used to fabricate anintricately shaped structure of the inner housings (500 a, 500 b) or theouter housings (502 a, 502 b). For example, a three-dimensional computermodel of any of the housings (500 a, 500 b, 502 a, 502 b) can be slicedinto thin cross-sections. The resulting cross-sections can be translatedinto two-dimensional position data that can be fed to control equipmentthat fabricates a three-dimensional structure in a layerwise manner. Theresulting three-dimensional structure may be formed from metal, such ashigh oxygen free copper, a thermoplastic/polymer based material, orother material. In an application in which thermoplastic material isutilized, an AM process may include calculating a path to extrude thethermoplastic material, which is then deposited in a semi-liquid stateas ultra-fine beads along an extrusion path. The material for thehousings (500 a, 500 b, 502 a, 502 b) may be selected according to adesired thermal conductivity or lack of thermal resistance. Thus,components that must withstand high temperatures during an operation ofa machine or apparatus in which the components are incorporated, can beproduced using metal AM or SFF manufacturing techniques.

Other AM processes that may be utilized include, but are not limited to:stereolithography; photopolymerization stereolithography; mask imagestereolithography; metal-sintering; selective laser sintering; directmetal laser sintering; selective laser melting; laser engineered netshaping; wire arc processes; electron beam melting; fused depositionmodeling; inkjet deposition; polyjet printing; inkjet materialdeposition; drop-on-drop material deposition; laminated objectmanufacturing; subtractive manufacturing processes; combined additiveand subtractive manufacturing processes; Arburg Kunststoff free forming;combinations thereof; and any other additive manufacturing processesknow in the art.

In order to simplify the manufacturing of components of the feedthroughassembly 300, each of the housings (500 a, 500 b, 502 a, 502 b) may bemanufactured to have an equal length, with each of the inner housings(500 a, 500 b) being identical, and each of the outer housings (502 a,502 b) being identical. A further advantage of this manufacturing schemeis that an operator assembling the feedthrough assembly 300 will nothave to make sure the right type of outer housing and the right type ofinner housing are be positioned closer to the first end 408 or thesecond and 410 of the main housing 406. Thus, assembly of thefeedthrough assembly 300 may be simplified by providing identical innerhousings and identical outer housings.

However, providing different types of inner housings and outer housingsmay also have advantages which may include reducing amounts of materialsrequired for assembly and overall cost of the feedthrough assembly 300.For example, the second inner housing 500 b could have a tapered endwith no inner central conduit, and the second outer housing 502 b couldalso have no outer central conduit. As a result, less second sealingmaterial 510 would be required to fill the main housing 406. In anothervariation, the second inner housing 500 a could be provided without atapered first end, and be identical in shape to the second outer housing502 b. In this arrangement, the second inner housing 500 b and thesecond outer housing 502 b may both be formed without a respectivecentral conduit. It will be appreciated that other configurations may beprovided that include inner and outer housings that are not identical.

It will be appreciated that the foregoing description provides examplesof the disclosed system and technique. However, it is contemplated thatother implementations of the disclosure may differ in detail from theforegoing examples. All references to the disclosure or examples thereofare intended to reference the particular example being discussed at thatpoint and are not intended to imply any limitation as to the scope ofthe disclosure more generally. All language of distinction anddisparagement with respect to certain features is intended to indicate alack of preference for those features, but not to exclude such from thescope of the disclosure entirely unless otherwise indicated.

We claim:
 1. A feedthrough assembly comprising: a main housing; a firstinner housing positioned within the main housing and defining aplurality of first inner conduits; a second inner housing positionedwithin the main housing and defining a plurality of second innerconduits; and a chamber defined by an internal surface of the mainhousing, a first end of the first inner housing, and a first end of thesecond inner housing that faces the first end of the first innerhousing, wherein each of the plurality of first inner conduits isaligned with a corresponding one of the plurality of second innerconduits, and wherein a cross-sectional area of the chamber varies alonga longitudinal axis of the main housing.
 2. The feedthrough assemblyaccording to claim 1, wherein the cross-sectional area of the chamberincreases from the first inner housing towards a center of the mainhousing, and wherein the cross-sectional area of the chamber decreasesfrom the center of the main housing towards the second inner housing. 3.The feedthrough assembly according to claim 1, wherein one of theplurality of first inner conduits is defined by the first inner housingas a first inner central conduit that is coaxial with the longitudinalaxis, and wherein the first inner central conduit extends from a secondend of the first inner housing to a first slot defined by the first endof the first inner housing.
 4. The feedthrough assembly according toclaim 3, wherein the first end of the first inner housing faces thefirst end of the second inner housing, and wherein a diameter of thefirst end of the first inner housing decreases in a direction along thelongitudinal axis from the first inner housing towards a center of themain housing to provide a tapered end.
 5. The feedthrough assemblyaccording to claim 4, wherein the tapered end includes tapered flanks,and wherein the first slot is defined between the tapered flanks.
 6. Thefeedthrough assembly according to claim 3, wherein one of the pluralityof second inner conduits is defined by the second inner housing as asecond inner central conduit that is coaxial with the longitudinal axis,and wherein the second inner central conduit extends from a second endof the second inner housing to a second slot defined by the first end ofthe second inner housing.
 7. The feedthrough assembly according to claim6, wherein the first slot extends along a first plane across a width ofthe first inner housing, wherein the second slot extends along a secondplane across a width of second inner housing, and wherein the firstplane is perpendicular to the second plane.
 8. The feedthrough assemblyaccording to claim 1, further comprising: a first outer housingpositioned within the main housing adjacent to a second end of the firstinner housing and defining a plurality of first outer conduits; a secondouter housing positioned within the main housing adjacent to a secondend of the second inner housing and defining a plurality of second outerconduits, wherein each of the plurality of first outer conduits isaligned with a corresponding one of the plurality of first innerconduits, and wherein each of the plurality of second outer conduits isaligned with a corresponding one of the plurality of second innerconduits.
 9. The feedthrough assembly according to claim 1, wherein theplurality of first conduits includes a central conduit and a pluralityof rows of conduits, wherein each row of conduits includes an annularrow of conduits surrounding the central conduit, and wherein each row ofconduits is radially spaced relative to an adjacent row of conduits. 10.A signal conveying system comprising: a plurality of cables; and afeedthrough assembly including: a main housing, at least one housingpositioned within the main housing and including an internal wall thatdefines a plurality of conduits, a volume defined by an internal surfaceof the main housing, and a sealing material provided in the volume,wherein each of the plurality of cables extend through the main housingand a respective one of the plurality of conduits, and wherein thesealing material and the internal wall isolate each of the plurality ofcables from one another.
 11. The signal conveying system according toclaim 10, wherein the main housing includes a first end and a secondend, wherein the sealing material includes a first sealing material anda second sealing material different than the first sealing material,wherein the first sealing material seals the second end of the mainhousing, and wherein the second sealing material seals the first end ofthe main housing and the plurality of cables within the at least onehousing.
 12. The signal conveying system according to claim 11, whereinthe plurality of conduits includes a central conduit and at least onerow of conduits defined around the central conduit, wherein an entirevolume defined by the central conduit is filled with the second sealingmaterial.
 13. The signal conveying system according to claim 10, whereineach cable includes: a core, a first sleeve positioned around the corewithin the main housing adjacent to a first edge of a length of thecable with the core exposed, and a second sleeve positioned around thecore within the main housing adjacent to a second edge of the length ofthe cable with the core exposed,
 14. The signal conveying systemaccording to claim 13, wherein for each cable, the length of the cablewith the core exposed includes: a first portion isolated within the mainhousing by the sealing material, and a second portion isolated withinthe main housing by the internal wall and the sealing material.
 15. Thesignal conveying system according to claim 14, wherein the at least onehousing includes an inner housing and an outer housing adjacent to theinner housing, wherein the plurality of conduits include inner conduitsdefined by the inner housing and outer conduits defined by the outerhousing, wherein each inner conduit is aligned with a respective outerconduit, and wherein for each cable: the second portion of the length ofthe cable with the core exposed is positioned in a respective innerconduit, and at least a portion of the first sleeve or the second sleeveis positioned in a respective outer conduit.
 16. The signal conveyingsystem according to claim 15, wherein each cable is surrounded by thesealing material within the respective inner conduit and the respectiveouter conduit.
 17. A method of conveying optical signals, the methodcomprising: providing a feedthrough assembly having a housing thatdefines a conduit and an optical fiber cable extending through theconduit, transmitting an optical signal through the optical fiber cablealong a substantially straight path defined by the optical fiber cablethat extends from a first end to a second end of the feedthroughassembly; and outputting the optical signal from the second end, whereinthe housing is positioned within the feedthrough assembly between thefirst end and the second end and supports the optical fiber cable toextend along the substantially straight path.
 18. The method accordingto claim 17, wherein the optical fiber cable includes an exposed core indirect contact with a sealing material that fills the feedthroughassembly and supports the optical fiber cable to extend along thesubstantially straight path.
 19. The method according to claim 18,further comprising conducting heat from the optical fiber cable with aportion of the sealing material that fills a chamber defined by thefeedthrough assembly.
 20. The method according to claim 18, furthercomprising conducting heat from the optical fiber cable with a portionof sealing material within the housing and an internal wall of thehousing defining the conduit.